City Walls
What was designed for a large number of people and therefore had a rather large city wall. They were built in the 3rd century along with the rest of the city.
The original walls protected Cosa not only from invasions by land, but also from raids by sea. The perimeter extended for nearly a mile and was reinforced by 18 towers for sighting, defensive and offensive action.
One thousand years after the site was abandoned, the Aldobrandeschi arrived, who, according to local accounts, found an imposing city wall that required no modifications on their part.
Of course, they still restored it in some places, but they could not finish it before the Sienese invaded.
After more than half a millennium, the walls were finally and meticulously finished at the end of the last century.
The present walls are made of large sandstone blocks. Most are the original Roman laid ones. Along the walls three doors and what used to be a post office, the first example of its kind in Italian history.
The 18 towers are still standing, although in various stages of decay. Those that faced the sea were rectangular, while the three that did not were circular.
The design of these walls was so clever that the Romans even had their own separate acropolis. It was situated to the south on a hill and surrounded by its own independent walls, with a single gateway from the interior.
A sewage system was also making its way in and out of the walls. It is an incredible architectural feat and shows exactly how industrious the Romans were.
